Gravity flow sintering machine



Oct. 24, 1950 w. KELsEY 2,527,309

f GRAVITY FLOW SINTERING MACHINE Fild March 22, 1947 s sheets-sheet 1 fff FREE ,van/R4L smPE L//vf o ,n l.

/m 47m/Mfr 0ct. 24, 1950 w. KELsEY 2,527,309

GRAVITY FLOW SINTERING MACHINE Filed March 22, 1947 5 Sheets-Sheet 2HHIHHHIIIIHHIIIIIIIIHHHIHIIILL Oct. 24, 1950 W KELSEY 2,527,309

GRAVITY FLOW SINTERING MACHINE Filed March 22, 1947 5 Sheets-Sheet 5STOCK SUPPL Patented Oct. 24, `1950 rUNITED STATESY PATENT OFFICE WalterKelsey, New York, N. Y. Application March 22, 1947, serial No. 736,487

This invention relatesto sintering machines.

The invention contemplates a gravity iiow sintering machine, thefunction of which is to sinter ores; in general, to sinter oragglomerate any materials that will sinter, and for any use. l In thesteel industry alone this machine is valuable in making usable, in theblast furnace for instance, low Igrade and crude iron ores, and wastefrom steel mills and shops The sintering machines at present in use areelaborate and costly to build and limited in their scope of use. Thepresent invention is simple in design and construction, less costly andhas a wide scope of use, and the operation is continuous. The stocksupplied to the machine, is, in general, a mixture of the material to besintered and a fuel, as well known.

The invention consists more particularly of an inclined sintering pass,in which the iiow of stock 'and sinter is regulated in consonance withthe sintering action, with its body portion subjected to an induced iiowof air, and having its upper end provided with a feeding chute. At thelower end of the feeding chute, the stock is ignited continuously andbrought to incandescence, by action of a iiame on the stock, whichignited stock is transposed to enable Ythe `transposed incandescentstock to sinter in the sintering pass under the action of the inducedair flow. The fire line is dis- 8 Claims. (Cl. 26S-20) ,posed betweenthe stock and the sinter, and the sintered stock is subjectedtocontrolling rollers or crushing means operating in consonance with theamount of stock sintered. The action throughout isA continuous,

v"Ihe invention will be further described, em,- `bodiments thereof shownin the drawings, and the invention will be nally pointed out in theclaims.

In the accompanying drawings,

Fig. 1 is a vertical sectional side view taken on line I-I of Fig. 3;

Fig. 2 is a diagrammatic partial view of two .suction chambers, one forsintering and one for cooling;

Fig. 3 is an inclined section taken on line3-3 of Fig.,1;

Fig. 4 is an inclined section taken of Fig. l;

Fig. 5 is an inclined section taken on line 5-5 of Fig. 1; Y Y

Fig. 6 is a vertical section taken on line 6-6 of Fig. 1;

Fig. 7 is a side View of the air lock plates;

Fig. 8 is a partial front view of the air lock plates;

on line 4-4 Fig. 9 is a diagrammatical view of the operation of certainof the essential features ofthe invention, and

Figs. l0 and 11 are diagrammatical partial views Vof different positionsof the i'lre `line..

Similar characters of reference indicate ncorresponding parts throughoutthe various views.

Referring to the drawings, the inclosed feeding chute I0 is eithervertical or sloping in such a manner that there is a gravity flow of thestock. The length of the feeding chute I0 between a gate II and anignition chamber I'I is such that there is no appreciable loss of airsuction through the stock held in the feeding chute IIJ.

As a means of preventing excessive compacting in the feeding chutehaving a stock guide, sections I3 forming pockets I3a filled with stockare provided in the feeding chute. The stock iiowing ,oif of the stockbody held in the pockets I3a moves with less force than if the stock hadan unimpeded flow. Also each pocket takes practically all of the weightof the stock within the chute vertically above the pocket.

To prevent the lower layer or part of Stock` in the bottom of thefeedingchute I0 from iowing ahead of the upper layer or part of stock inthe chute, a row of chains I4 is hung in the feeding chute. These chainsI4 are so hung that they will lay in the lower layer of owing stock orin the bottom |021 of the feeding chute and furnish enough resistance toretard the flow of this lower At the bottom VI2 of the feeding chuteYIl) the top surface of the stock is not restrained and takes its naturalslope as it passes below an ignitor or ignition ame I'Ia either in theopen or in an ignition chamber I'I, and then as an ignited stock ornewly made sinter 52 the top surface of which 53 (see Fig. 9) passesbelow an air cooling intake I9 with a iiow adjusting damper ISa, andthence below the plunger 2I or other transposing means.

The ignition chamber I1 is so. made as to burn the fuel used to a flame.The flame is impinged y upon the exposed surface of the stock descendingin the feeding chute throughout its width so as to properly ignite thestock while it passes below thechamber Il. suction aids to draw tinuityof the ignited stock or sinter.

l and l1. bulk of the stock pushes the` inclined fire line Ia ltowardsthe yfront side of the sintering pass into 3 rier is adjustable by aslide 20a clearing the sintering stock as it ows underneath.

Instead of the ignition chamber an open flame may be used impinging onthe stock, and disposed above the barrier 20 with its slide 20a.

The air blast intake I9 is made to force a blast of air directly uponthe hot surface of the ignited stock or sinter 52 with the object ofcooling its surface 53 under retention of a fire line 5I, so it will notadhere to a flow-directing plunger or other transposing means, abouttobe described.

At the top of the sintering pass I5, the ow of the ignited stock orsinter is transposed in position, and that ignited stock or sinter whichwas the front layer located above thevbulk ofthe moving stock in thefeeding chute now becomes the front layer locatedbelow the bulk of themoving stock in the sintering pass I5. Forthis purpose, a power drivenplunger 2l or other power driven device is placed in the front side, atthe top of vthe sintering pass I5. This plunger n2| has an inclinedportion 55 (see Fig. 9) to facilitate the transposal of the sinter andlire line, and forces the newly made sinter with its A'dre line or the'adjacent ignited stock, down along-'the front side of the sinteringpass I5 at such a-speed kas'to match the flowof the rest of the ignitedstock so as not to breakthe con- The inclined side of the plunger pushesthe nre line 5I into an inclined, position` 5Ia, as shown in Figs. Thenthe plunger withdraws. The

theposition 5Ib. While theplunger withdraws, the initial `fire line -5Ifkeeps' on moving in the same vdirectionas when formed. When the endreaches'thefront side of the sintering pass, the next movement of theplunger moves it tothe inclined position 5Ia.` Thence the sinter andignited stock and Yunburned 'stock' continues to `flow or slide down onthe front side of the inclined sintering lpass. Upon the induced airacting upon thel'lre 'line land superposed stock, the fire line-6I) risjdrawn along and sinters the superposed stock. Astheistock and thesinter flows down the sintering pass I5, the fire line 6U takes a meandiagonal position, until the 'superposed-"stockis entirely sintered. Theunburned stockis'restrained bythe back side I5c of the 'sintering passfor a` suitable' length.

To prevent excessive Vcompactingat the point of transposalof` flow, thebottom ofthe feeding chute is made to *project` as shown at 22 beyondthe lowerface ofthe backside I5c. This will Yleave a portion ofstockwithout any direct vertical' load with onlythe'side pressure toforce this `portionof the stock b ack against the back side. A,Thisgives'a release vfor the sidevpressure developed by the 'corner plunger2| or other turning device. `In the embodiment, the plunger 2| hasalinkZI'a pivoted to a crank arm 2 Ib operated by a shaft 2Ic;

'Thesinter and `stock in the sintering pass I5 istraversed by an airflow-'fora space equal to the length of the air chamber 29. "The inducedair ows from` the' front of 4the air chamber 29 throughthe perforationsI5b in the wall I5a and 'transversely ythrough the-entire lwidth of thechamb erv 3U.

to cool the sinter. The speed of stock flow and amount of air or draftis so adjusted that the fire will burn entirely through the stock.Sintering, which begins at the ignition llame, is completed at a point 0below the lower end of the back side I5c, at which place the stocksurface is not restrained, and the top surface of the stock ilows freeat its natural slope. In front of the fire line '59 and below the pointU Where the re has burned through, allthe stock;V has become rigidsinter and its plastic character having been lost by the cooling, itwill ilow or slide down to ,controlling crushing rollers 24 and 25, andwhen crushedV to a conveyor 26. The cooled and hardcned sinter isgripped and handled by the power driven controlling rollers 24 and 25.

Over the free surface of the sinter below the suction chamber, air locks23 are arranged. The length of the sinter pass from the bottom of thesuction chamber to below the lowest air lock 23 is such that there is noappreciable loss or airsuction through the sinter or stock held in thesinteringpass I5.

vThe controlling and crushing rollers 24 and'25 are driven at such speedas to give the desired flow of Istock in the sintering pass. Known,means `(not shown) are provided for changing conveyor 26 dischargesthesinter into the screen 2l vor processing room. The pan conveyor26 isthe preferred formbut other forms of conveyor may be used. rlhe controland crushinglmeans may be modifiedasto the meansshownfbut the controlfeature is important.

The air flow induced from the ignition chamber I'I by the suctionchamber 30, and from ther air chamber 29 bythe suction chamber .30, isproduced by asuctionfan 34. The frontside of the air chamber 29 isindicated by 29a.. The front side |50. isr perforated by holesI5b, thelocation and number of which is established by ,the requirements ofsinteringand the demand for air along the front side I5a. The bottom Iaof the lower part of the feeding chute I0 and the back side I5c ofthesintering -pass are. also Yperforated vwith .holes I5d, the locationsize.. and number of which .lis established .by theamount of air whichisA to4 be allowed to pass.

Anequalizing damper 354s placed in the suction This .damper 35 extendsfrom end to end of the chamber- 30 andvtsloverlthe backside #5c of-thesinte'r-ing -pass toequalize thel airilow, or giventhe suctiondesired, tor bring the fire to the surfaceof'thestock at'the desiredlocation D and to allow ample air for the cooling of the'fsinter. Thisdamper 35 isarranged to be raised or lowered by known regulatingdevices-35a ateither end to equalize air ow and to compensate for anyeccentric end ldraft from the'suctionduct'. Thus, this equalizing damper35 provides means to bring the re to the surface of the stock yat thedesired location 0. Y

lIfhe air lock 23 which is placed where thesinter leavesV the suctionchamber, consists of flat-plates 3l suspended close together on a shaft138 (Figs. '7 and 8) The bottoms of these heavy plates rest on andutakethe irregularities of the topof the sinter as it passes underneath.ThereA isvery little open space for the passage of air. One llock ormore locks may be used, in series if necessary. In Fig. 2 is shown aseparate suction chamber 30h ammo@ controlling theair lock arrangement,having a Vfan 34a inthe outlet channel casing |5e. Y j 'When the'gravity' flow sintering machine is `in operation; the feeding chutean'd'sintering pass is full of stock and sinter. The stock fromv thesupply atithegate and4 that in the machine puts'a pressure onthecontents of the machine which acts to force the stock and sinter downthrough themachine. .This force, which is gravityacting on thematerials, forces the stock and sinter to follow downward `throughthemachine as vsinter isdischarged from the bottom of the sintering pass by.the controlling and crushing rollers* This discharging from thebottomof the rigid sinter acts to reduce the compacting of the stock inthe upper part of the sintering pass.`

`With' the exception of the retarding'pocket or pockets |3a. there is noplace in the machinefor the collectionor holding of stock. The machineis self-cleaning. and clearing when operated for this purpose.

'lhismachine may be so built as to be pracv` ticallydust proof. Theinclosure which can in`r` cludefthe screen or processing room may havethe dust. ,ladened air kdrawn into the air chamber through-an air intake39 adjusted by the regulatorj.39a.. The air and gases resulting from thesintering' process may be run through a dust collector either before or4after the suction fan. The air. intakes i9 and 39 to the air chamber 29are so adjusted that the one I9 at the ignition chamber will havesufficient air passing to givev desired coolingblast for the. sinter. yY

Hot sinterwillbe .in contact with the plungerV 2|; the-top of `the frontside and with parts of the ends 6| of the sintering pass. The metal atthese places including the plungers and supporting parts thereof is heatresisting and a metal to which the hot sinter'will not readily adhere.

The operation is as follows: To start the gravity flow sinteringmachine,fthe stock supply gate is opened filling the entire machine withstock. IfV the machinery is not running, the machine will stand full ofstock as the conveyor 25 at the bottom is so placed that the stock willtake its natural slope below the rollers and be held on the conveyor 26as indicated by lines4 24a. and 25a. When the machine begins to operate,the conveyor will carry the stock away at a velocity to givethe stockthe desired speed for the downward flow in thesintering pass.` Thesuction'fanv 34 is now started and the ignition fiame |'|a is nowignited. Sinter obtained bythisiiame ignition and maintained by the airsuctionV will follow the stock, as indicated by the fire line 60,through the sintering pass. -Any stock going through the machine withoutbeing converted to sinter is separated from the sinter and is returnedto the stock processing line. YPartial loss of fire orignition doesnotstop the process as the-stock and -sinter both pass through the'machineat the same velocity, thus allowing Va pick up in ignition. However, themachinery must run and the ignition. flame must be maintained to producea continuous output of sinter. f

In Fig. 9 is shown diagrammatically the incom' ing flow of the stock,into the gravity acting in-v clined( sintering pass |5. When the stock50 is ignited by the actionofthe ignitor Ila. upon the descending stock50, a fire line 5| is formed contiguous to which the sintered stock 52is formed, which increases indepthdue to the action of theincandescence. When thel Vflame Ila strikesthe stock, or is impingedagainst the stock, the incandescence is from the flame adjacentsurfaceinwardly into the stockt When' the sintering 4material andstockisrsubjected to an 'induced air flow, as through wall Illa, thedesideratum is to pull the incandescencel into the unsintered stock. l

The surface 53 of this incandescent portion 52 is cooled by an air flow54 (Figs. 9, l0 and 11). The lower end of this cooled surface 53 issubjected to the action of a plunger 2|. This plunger changes the flowof the sintered stock 5'2. `It acts as a sinter flow director. Thesurface of the sinter stock 52 corresponding tothe inclined face oftheplunger 2|, is indicated by 53a, and this surface 53a, is diverted bythe plunger 2|, which directs the firing line 5| to the position 5|a, soas to be at an angle to its original direction. Uponl the withdrawal ofthe plunger 2|, the firing line 5| a is pressed by the downwardly movingstock to the position 5|b, and'initiates the ring line 6i).

In Fig. 10, the plunger 2| engages the surface 53 forcingthe sinter andincandescent layer 52 (see Fig. 9) and stock downward along the frontside of the sintering pass to the position between 52A-52B with thecooled surface 53a in contact Iwiththe plunger 2| at the low positionof` plunger 2|. As the plunger 2| returns to its high position, thesinter and incandescent layer between 52A-52B is forced down against thefront side |5a by the pressure of the stock 50 in the feeding chute.This-cycle is repeated with each stroke of the plunger 2| and places thecooled surface of the sinter against the front 'side |5a of thesintering pass l5 with the incandescent layer and stock above instead ofbelow the sinter. Due to the induced air ilow and descent of the' stock,the incandescent layer or re line then takes an inclined line 69.

In Fig. 9 is shown the initial position of the iiow of the ignited stockdown to the front side 55a. In Fig. 10 the down `position of the plunger2| is shownwhereby the cooled surface sinter 53a` and the incandescentline 5| is diverted to the angular position shown. On the return of theplunger, there is a space left. The .pressure of the stock then forcesthe sinter and re line 5| downwards against the front side |5a, as shownin Fig, 11. The action of the plunger is intermittently continuous andits next descent then again acts on the -Inaterial asvshown in Fig. 9,which' material has in the meantime entered the space referred to andthen is subjected to the action shown in Fig. 11.

Thus the vmachine takesV the prepared stock from a supply, passes thisstock by gravity flow through an inclosed feeding chute so that thestock passes an ignition flame and continues the gravity iiow, thefeeding' chute above and the air locks below forming airthrottling-portions, one at each end of the sintering pass acted uponcon by the induced air.

From theforegoingitis seen that Vthe invention includes a gravity flowsintering machine,`

in which the prepared stockfor thesame flows by gravitythrough asubstantially vertical inclosed Y 55a feedingl chute blocking olf theair flow, with the stock feeding into an inclined sintering pass..

The bodyof the stock prior to its passage into the sintering pass, is`continuously acted yupon by;

a flame to ignite a locally exposed upper surface in its new or slidingthrough the.

of the stock. Thisignited and burning surfacev of stock is turned byturning means lwhile in af plastic and burniniT condition to become thehard lower surface of the body ofistock, from which a re line is formeddividing the stock The. body of sinter and stock divided bythe fireline. by; being traversed'transversely by air, enablesthecombustionltorbe continuously carried on, andpnthe completionthereof, to be cooled, as these materials flow down the-.sintering pass,producing a practically rigid block of sinter, furnishinga blocking.oil" of airflow at its lower end. This block of sinter is engagedA bythecontrolling and crushing means and is discharged bythe same from thesintering pass. The action iscontinuousvfrom the feedingof the stock tothe crushingv of thelsinter, with the crushing car.- ried' on.relatively to the amount of sinter being produced, or converselystated, the crushingl is regulated to bring about a co-related amount ofsintering.

It will also be noted that in the feeding chute thefilarne action orignition of' the stock at the ignition chamber is with Aiiame above thestock and the nre line drawn downwards by the air suction, but in thesintering pass the ignited stock is below the stock mass and the re lineis drawn upwardly, these separate actions taking place at about 90 toeach other.

It will be noted that the front side la with its openings |519 extendsbelow the lower end of the backside l5c with its openings ld.y The uppersurface of the stock below the lower endof the back side l5c is free andunrestrained, but is Subject to the suctionaction of the suction chamber30. When the stock has been sintered, the upper surface of the sinter isfree and unrestrained, and the upper part of the sinter in the sinteringpass is subject to the suction chamber 3U. When a second suction chamberis used as shown by Fig. 2, air exhaust is taking place-by fan 34a, forinstance, the upper air lock 23 acts as a barrier or separating meansbetween the two suction chambers. This air lock acts as an air choke, orprovides an air choking action. The fan 3A0. sucks air from the loweropenings I5b of the front side I5a, and the sinter is thereby cooled.

The feed chute as described prevents air from being sucked in, and thusalso actsV as an air Crusher 25, transmits power to the shaft of theroller 24, and to the drive shaft of the conveyor 26, and to the driveshaft 2lc of the plunger, in order to have these parts act in unison,suitable linkage being utilized.

I have described several forms of my invention, but obviously variouschanges may be made in the details disclosed without departing from thespirit of the inventionas set out in the following claims.

I claim:

l.' In a sintering machine, an enclosed stock feeding chute, verticallydisposed, including a vertical stock guide having a vertical wall and anadjacent horizontal wall, said horizontalwall forming with its adjacentvertical wall a flow retarding pocket at the lower end of the first inga vertical wall and an adjacenthorizontal wall, said horizontal wall'forming with its ad-,\

jacent vertical wall a flow retarding pocket at the lower end of thesecond stock guide, disposed laterally out of vertical alignment withthe first stock guide for directing the stock at an angular direction tothe vertical ow of the first stock guide, an inclined wall between thepockets for directingethe stock ow at an angular direction to thevertical ow in the second stock guide', an ignition chamber'atthe lowerend of the inclined wall having an opening along the upper part of thestoclcflow for'igniting the stock, an opposed inclinedwall having airopenings for sup'porting the stocky flow, and a suction chamber belowhorizontal wall forming with its adjacent verti-V cal wall a -flowretarding pocket at the lower end of the second stock guide, disposedlaterally out of yvertical alignment with the rst stock guide fordirecting the stockat an angular directiony tothe vertical flow ofv thefirst stock guide, an

inclinedtwall between the pockets for directingthestock flow at anangular direction to the ver-4l tical flow in the second stock guide, anignition chamber at the lower end of the inclined wall having lanopening along the upper part of the stock -fiow for igniting the stock,an opposed inclined wall having air openings for supporting the :stockflow, a suction chamber below the lastv named inclined wall for drawing'air from the ignitedpart of the stock through' the stock flow, and acooling device below the ignition chamber and adjacent to the same, forcooling the ignited stock,.and disposed out of the aforesaid air ow.

3. Ina sintering machine, an enclosed stock feeding'. chute, verticallydisposed, including a vertical stock guidel having a vertical wall andan adjacent horizontal wall, said horizontal Wall forming ywith itsadjacent vertical wall a flow retarding.pocket at the lower end of therst stockguide, a second vertical stock guide, havinga vertical wall andan adjacent horizontal wall,-said horizontal wall forming with itsadjacent vertical wall a ow retarding pocket at the lower: end of thesecond stock guide; disposed laterally out of vertical alignment withthe first stock guidel for directing the stock at anangular direction tothe vertical flow of the first stock guide, an inclined wall between thepockets for directing the stock ilow at an angular direction to thevertical iiow in the second stock guide, an

ignition chamber atfthe lower end of the inclined wall having an openingalong the upper part of the stock-flow for igniting the stock, anopposed inclined wall having air openings for supporting the stock flow;a suction'chamber below'the last named inclined wall for drawing airfrom the ignited part of the stock through the stock iiow, a sinteringpass for the flow of stock having parallel4 perforated topand bottomwalls with closed side walls, inclined to the perpendicular, and a 5suction chamber on a wall of the sinter pass for drawing air through theys'tock'in the sinterpass through' the'penings of a wall of the sinterpass', whereby the stock descends by gravity from the chute, passes theignition chamber and passes through the sinter pass to its discharge atthe loweriend ofthe sinter'pass in the form of sinter.

4. In a sintering machine, anenclosed stock feeding chute, verticallydisposed, including al vertical stock guide having a vertieal'wall andan adjacent lhorizontal Wall, said horizontal wall said horizontal` wallforming with its adjacentr vertical wall a flowY retarding pocket atthelower end of the` second stock guide, disposed laterally out oflvertical alignment with they first stock guide for directing the stockat an angular direction to the flow Vof the first stock guide, a rstinclined wall between thel pockets for directing the stockiiow at anangular direction to the perpendicular in line withthe discharge flow inthe second stock guide, a second inclined wall extending from the secondhorizontal wall, downwardly substantially parallel with the firstinclined wall',` an ignition chamber-at the lower end of the firstinclined wall having an opening alongthe upper part of the stock, flowfor igniting the adjacent sur-face of the stock, said secondinclinedwall having air openings; asuction chamn ber below the lastnamed inclined wall for drawn ingair from the ignited part of the stockthrough the stock flow, a sinter pass for the flow of the ber,consisting of a pusher, for transposing the ignited surface of the stockfrom its direction along the first inclined wall adjacent the ignitionchamber to a direction along the front wall of the sinter pass, the saidinclinations of all of said inclined walls being such as to retard butnot to prevent the flow of stock under the action of A gravity, wherebythe stock descends in mass, passes the ignition chamber and passesthrough the sinter pass to its discharge at the lower end of the sinterpass in the form of sinter, being -f propelled in such passage by theaction of gravity.

5. In a sintering machine, the combination of a vertically disposed feedohutefor stock having spaced front, rear and side walls, and having anopen top and an opening at its lower end, with means discharging thestock at an inclination to the perpendicular, an ignition device forigniting the adjacent'free upper surface of the stock flowing from saidmeans in a mass discharging from the end of said means owing along saidignition device, an inclined sinter pass having an open top incommunication with said chute discharge means, for receiving the stockpassing along the ignition device, said sinter .pass having parallelperforated front and rear walls and closing side walls, said frontsurface of ignited stock mass being unimpeded to flow until it rests onthe top of the front sinter pass wall, means for transposing the saidfront surface of said ignited stock at the top of the front sinter passwall from a position above the stock as it moves from the ignitiondevice to one below the stock along the front sinter pass wall, saidmeans including a pusher having a pusher surface angularly disposed atan acute angle to the upper inclined surface of the stock as itimovestowards said front wall flowing from said ignition device and disposedat an obtuse angle to the front wall of said sinter pass, and means forintermittently operating said pusher, whereby when the pusher ieg ismoved downward in a direction parallel to the front wall of the sinterpass, the ignited surface of the stock flowing from saidignitiondeviceis pushed into the lower part of the sinter stock of the sinterpass, and is held down by the stock in thes'inter ypass .to a positionin the sinter pass below the stock therein,v and when the, pusher ismoved in the reverse direction ignited stock flowing from the ignitiondevice moves in front ofthe` pusher.

. .6. In'a sintering Vmachine, the combination of a vertically disposedfeed chute forstock having spaced front, rear and side walls, andAhaving an open top and anopening at its lower end, with meansdischarging the stock at an inclina` tion to the perpendicular, anignition device for igniting ,the kadjacent free upper` surface of thestock lovving'from said means in a mass discharging from the end of saidmeans owing along ,said ignition device, an inclined sinter 'pass havingan open top in communication withsaid chute discharge means, forreceiving the stoclr` passing along the ignition device, said sinterpass having parallel perforated front and rear walls;

and'closing side walls, said front surface Vof,.ig nited stockmass being.unimpeded to flow until it rests on the top of the front sinter passwall, means for transposing the said front surface of said'ignited stockat `the top of the front sinter pass wall from a position above thestock as it moves from the ignitiondevice to one below the stock alongthe front sinter pass wall, said means including a pusher having apusher surface angularly disposed at an acute angle to the upper l,inclined surface of the stock as it moves towards said front wallflowing from said ignition device and disposed at an obtuse angle to thefront wall of said sinter pass, and means for intermittently operatingsaid pusher, whereby when the pusher is moved downward in a directionparallel to the front wall of the sinter pass, the ignited surface ofthe stock flowing -from said ignition device is pushed into the lowerpart of the sinter stock of the sinter pass, and is held down by thestock in the sinter pass to a position in the sinter pass below thestock therein, and when the pusher is moved in the reverse directionignited stock flowing from the ignition device moves in front of thepusher, with an extension of the angular rear wall above the sinter passinto the sinter pass space at the upper end ofthe rear wall of thesinter pass, this extension forming an acute angle with the rear wall ofthe sinter pass providing a space free from the direct gravity flow ofstock between said extension'and the rear wall of the sinter pass,whereby any pressure by the pusher on the stock is relieved and taken upin the said space.

7. In a sintering machine, the combination of a gravity iiow sinter passincluding a front wall, a parallel rear wall spaced therefrom, and sidewalls connecting the front and rear walls forming an elongated chute forguiding stock in the mass throughout its cross-section, having an openupper receiving end, and an open lower discharging end, said front wallhaving an inclination to the perpendicular to retard but not to preventthe descent of the stock by gravity from the open upper receiving endtowards the lower discharge end, a feed chute having an elongated upperportion of vertically disposed walls open at the top of said portion toreceive the stock and open atthe bottom of said portion to discharge thestock, for enclosing stock throughout the cross-section of said portionfrom said top il to said bottom in vertical flow providing an air choke,said feed chute having a vertically dis'- posedy lower portion ofsubstantially vertically disposed stock-enclosing walls, said wallshaving an opening at their upper end and with a discharge opening attheir lower end, below lsaid upper portion and in continuationtherewith, to

receive the stock discharged from thel bottom of said upper portion,said last named lower portion having an inwardly extending horizontalwall in the vertical downward path of the discharge of the upperportion, the lower portion below said horizontal wall being disposedlaterally out of vertical alignment with the upper portion for directingthe stockflow in a direction in an angular direction to .the verticalflow of the upper portion, all portions of the feed chute from ,its topYto its bottom forming. avcontinuous air tight enclosure with thestocktherein forming anoverall air choke, said feed chute being above thesinter 'pass receiving en d and having, the discharge opening of itsllower portion in ,stock communication with the open upper end of thesinter pass and adjacent thereto, a stock igniting device above the freeflowing surface of said stock asit discharges from the feed chute intosaid sinter pass, for igniting the surface of said stock adjacent saiddevice, and means supplying air to the stock in the sinter pass chutefor continuing the burning of the stock in the sinter pass 30 during theflow of the stock ink the sinter pass chute until the stock in saidsinter pass chute is converted to sinter, the discharge of the sinterbeing from the lower end of thesinter pass, said sinter acting as an airchoke in the lower end of the sinter pass.

8. The structure of claim 7, with sinter break-- ing roller means atsaid lower discharging end of the sinter pass for breaking the sinterdischarging from the lower end of the sinter pass, and means varying thespeed of said sinter breaking means, whereby the movement of the stockin the sinter pass is controlled.

WALTER KELSEY.

REFERENCES CITED The following references are of record inthe le of thispatent:

UNITED STATES PA'I'Eiv'rsvv l Date v

